JP2006-168400A (Patent Document 1) discloses (a) detecting presence of abnormality in an electromagnetic suspension unit that is equipped with an electric motor, by comparing an estimated value of a sprung-portion acceleration and an actually detected value of the sprung-portion acceleration, and also (b) detecting presence of abnormality in the electromagnetic suspension unit, by comparing an estimated value of a rotational angle of the electric motor and an actual value of the rotational angle of the electric motor. The estimated value of the sprung-portion acceleration is a value that is estimated based on an actual value of an acceleration of a wheel-side portion in a vertical direction by utilizing an observer.
JP2005-254940A (Patent Document 2) discloses detecting presence of abnormality in an electromagnetic suspension unit that is equipped with an electric motor, based on whether an actually operating amount of the electric motor (rotational angle of the motor or amount of change of stroke of the motor) is within a range that is dependent on a control value based on which the electric motor is controlled.    [Patent Document 1] JP2006-168400A    [Patent Document 2] JP2005-254940A